Process applications generally involve a series of actions or steps that are taken in a prescribed sequence in the development and/or manufacturing of a product. Such processes are repeatable and predictable, or at least are generally intended to be. In a wide range of fluid handling process applications knowledge of process conductivity or other fluid characteristics is a valuable piece of information. Such measurements are of particular interest in the technology field of biopharmaceutical process applications for both product development and manufacturing.
For example, in order to measure conductivity in a fluid stream, an in-line gauge is traditionally provided somewhere along the fluid flow path. However, the use of an in-line gauge is not optimal in some process applications. For example, when using lightweight flexible tubing, such in-line devices can be bulky, weighty or too intrusive. Alternatively, to measure conductivity and/or temperature in a vessel, a gauge is inserted into a vessel port. However, in a lightweight, collapsible thin-walled vessel, such a bag insertion of a traditional gauge is not optimal
Additionally, many fluid process applications in biotechnology require a fluid handling environment with minimal microbial contamination. It is important to ensure that an uncontaminated environment has been maintained throughout the process. Thus, in critical processes, such as production in bioreactors, filtration, chromatography, and formulation and filling of containers or vials, knowledge of the conductivity or other fluid characteristics in the process is critical, but an uncontaminated environment must be maintained.
One method of maintaining an uncontaminated environment is to employ critical assembly elements that are designed for single-use (or limited use). Thus, such an assembly could contain a large variety of components such as flexible tubing, single use process containers, such as plastic/polymeric bags. Such bags are commonly used in biotech processes for storage of fluids and mixing.
These process bags are typically made of polymeric film materials such as polyethylene (PE) film material and are often provided with port plates, which are attached to the film material before the material is made into a bag. The plates are also made of a similar molded polymeric material and are melt-sealed to the film for the required penetrations for tubing, sample ports, etc.
As mentioned above, there is often a need to measure a physical characteristic or parameter, such as conductivity and/or temperature, of the fluid within a process system, and such measurements are typically taken by sensors provided somewhere within the tubing defining the fluid flow path.
However, in certain instances, it would be desirable to measure such characteristic or parameter of the fluid within the process bag, particularly for mixing of fluids with salts for critical processes or making an addition to adjust a parameter of the fluid. However, the polymers used for fabricating innovative plastic in-line conductivity sensors may be of a material that cannot be heat sealed to the film material. Moreover, adhesives or glues of any type would not be desired in such contamination-free environments and would likely not even work. Also, if sterilization is required, many single-use process bags are not compatible with most heat sterilization temperatures so gamma or ethylene oxide (ETO) processing is typically used so the process sensors should be compatible with gamma or ETO processing.
It is therefore desirable to provide a sensor that is suitable for simple and easy removable connection with a biotech process bag, while providing the ability to accurately measure properties, such as conductivity and/or temperature, of the fluid within the bag. Also, the sensor and bag fitting must be easy to use, inexpensive and universally adaptable to numerous applications.